1. Field of the Invention
The present invention relates to a method for correcting data used for controlling the operation of a vehicular clutch, and more particularly to a method for correcting learned data for clutch control operation.
2. Description of the Prior Art
In the prior art there has been widely used a clutch control system for controlling the operation of a friction type clutch in which the clutch is coupled with an actuator and the amount of operation of the clutch is controlled by the actuator in accordance with an electric control signal generated by a control unit. The clutch control system of this type is employed in, for example, a vehicle automatic transmission system. In the case where the operation of the clutch is controlled by the use of the clutch control system of this type, precise clutch data corresponding to the relationship between the position of a member for operating the clutch and the amount of operation of the clutch is required to ensure appropriate clutch control operation. However, variation in this relationship arises because of variation in manufacture, and also with the passage of time due to the wear of the clutch disc and the like.
Accordingly, if precise control of the clutch is required, it is necessary to carry out appropriate correction of the clutch data representing the relationship by, for example, a learning operation. In the prior art, for correcting such clutch data, the meet position of the clutch pressure plate, at which the rotation of the input shaft of the transmission starts because of the transmission of torque through the clutch owing to the meeting between the pressure plate and the associated clutch disk, is determined by a learning operation which is, for example, conducted each time the selector is set to its neutral (N) position, and the clutch data necessary for controlling the clutch is corrected by the use of the resulting learned data to obtain the corrected or up-dated clutch data.
In general, in the case where the clutch data is corrected on the basis of the learned data as described above, the newly obtained learned data is not directly used for the correction as it is. Instead, the clutch data is corrected by the use of up-dated data obtained by processing the newly obtained learned data in accordance with, for example, the moving-average method, so that even if the learned data includes a large degree of error, the error is not directly reflected in the correction of the clutch data.
However, the foregoing conventional method has a disadvantage in that the correction value is determined by taking into account the learned data obtained previously even if the newly obtained learned data represents precisely the data required for the correction of the clutch data, as may be the case, for example, following the adjustment or replacement of the link mechanism between the clutch and the associated actuator. In such circumstances faulty data correction is first carried out and then the clutch data is gradually corrected so as to approach to the appropriate value. Accordingly, in this case, improper clutch data is provided for controlling the operation of the clutch for a long time and the clutch is not controlled properly until the clutch data reaches the appropriate data.